Effects of supply with glutamine on antioxidant system and lipid peroxidation in patients with parenteral nutrition

Introduction: In the critically ill patient, there is a continuous production of reactive oxygen species (ROS) that need to be neutralized to prevent oxidative stress (OS). Quantitatively speaking, the glutathione system (GSH) is the most important anti-oxidant endogenous defense. To increase it, glutamine supplementation has been shown to be effective by protecting against the oxidative damage and reducing the morbimortality. Objective: To assess the effect of adding an alanylglutamine dipeptide to PN on lipid peroxidation lipidica and glutathione metabolism, as well as its relationship with morbidity in critically ill patients. Methods: Determination through spectrophotometry techniques of glutathione peroxidase, glutathione reductase, total glutathione, and maloniladdehyde at admission adn after seven days of hospitalization at the Intensive Care Unit (ICU) in 20 patients older than 18 years on parenteral nutrition therapy. Results: The group of patients receiving parenteral nutrition with glutamine supplementation had significant increases in total glutathione (42.35 +/- 13 vs 55.29 +/- 12 mu mol/l; p < 0.05) and the enzymatic activity of glutathione peroxidasa (470 +/- 195 vs 705 +/- 214 mu mol/l; p < 0.05) within one week of nutritional therapy, whereas the group on conventional parenteral nutrition did not show significant changes of any of the parameters studied (p > 0.05). However, both mortality and ICU stay were not different between the study group, whereas the severity (asessed by the SOFA score) was lower in the group of patients receiving glutamine (SOFA 5 +/- 2 vs 8 +/- 1.8; p < 0.05). Conclusions: Glutamine intake in critically ill patients improves the antioxidant defenses, which leads to lower lipid peroxidation and lower morbidity during admission at the ICU.